Muscle contraction Flashcards Preview

Year 1 Cell Biology > Muscle contraction > Flashcards

Flashcards in Muscle contraction Deck (14):
1

What molecule is liberated into the synaptic cleft by synaptic vesicles?

Acetylcholine

2

What occurs when Ach binds to receptors on the post-synaptic membrane?

1. Na+ ions enter the cell2. K+ ions leave the cell3. Sarcolemma depolorizes

3

What protein is contained within the sarcoplasmic reticulum?

Calsequestrin

4

Where is calsequestrin located?

Sarcoplasmic reticulum

5

What is the role of calsequestrin?

Stores calcium ions and liberates them into the cytoplasm, in the region overlapping thick and thin filaments (goes from SR and into cytoplasm)

6

What subunit of troponin do calcium ions bind to?

TnC

7

What happens when TnC binds calcium ions?

1. TnT pushes tropomyosin filaments to move deeper into the spiral groove of actin, exposing actin active sites2. Myosin head associates with actin monomer (ATP expended)3. Head and neck of myosin bend4. Myosin pulls the actin filament over the myosin filament, resulting in sliding of thin filament toward midline of sarcomere

8

What happens to the length of thin filaments during contraction?

Remains the same!

9

What happens to the length of thick filaments during conraction?

Remains the same!

10

During contraction, what happens to the A band?

Remains the same size

11

During contraction, what happens to the H band?

Almost disappears

12

During contraction, what happens to the I band?

Becomes smaller

13

During contraction, what happens to the Z discs?

Approaches midline

14

What happens during rigor mortis?

Actin-myosin complexes cannot dissociate since ATP is not available - muscles stiffen